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Commit d8a7e59e authored by TreeHugger Robot's avatar TreeHugger Robot Committed by Android (Google) Code Review
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Merge changes from topic 'blobcache'

* changes:
  convert BlobCache to STL
  move BlobCache over (unmodified) to libEGL
  Remove dependency to most of libutils
parents 5f842f49 b7f9a240
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@@ -105,9 +105,20 @@ cc_library_shared {
        "EGL/egl.cpp",
        "EGL/eglApi.cpp",
        "EGL/Loader.cpp",
        "EGL/BlobCache.cpp",
    ],
    static_libs: ["libEGL_getProcAddress"],
    ldflags: ["-Wl,--exclude-libs=ALL"],
    export_include_dirs: ["EGL/include"],
}

cc_test {
    name: "libEGL_test",
    defaults: ["egl_libs_defaults"],
    srcs: [
        "EGL/BlobCache.cpp",
        "EGL/BlobCache_test.cpp",
    ],
}

cc_defaults {
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/*
 ** Copyright 2011, The Android Open Source Project
 **
 ** Licensed under the Apache License, Version 2.0 (the "License");
 ** you may not use this file except in compliance with the License.
 ** You may obtain a copy of the License at
 **
 **     http://www.apache.org/licenses/LICENSE-2.0
 **
 ** Unless required by applicable law or agreed to in writing, software
 ** distributed under the License is distributed on an "AS IS" BASIS,
 ** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 ** See the License for the specific language governing permissions and
 ** limitations under the License.
 */

//#define LOG_NDEBUG 0

#include "BlobCache.h"

#include <inttypes.h>

#include <cutils/properties.h>
#include <log/log.h>
#include <chrono>

namespace android {

// BlobCache::Header::mMagicNumber value
static const uint32_t blobCacheMagic = ('_' << 24) + ('B' << 16) + ('b' << 8) + '$';

// BlobCache::Header::mBlobCacheVersion value
static const uint32_t blobCacheVersion = 3;

// BlobCache::Header::mDeviceVersion value
static const uint32_t blobCacheDeviceVersion = 1;

BlobCache::BlobCache(size_t maxKeySize, size_t maxValueSize, size_t maxTotalSize):
        mMaxKeySize(maxKeySize),
        mMaxValueSize(maxValueSize),
        mMaxTotalSize(maxTotalSize),
        mTotalSize(0) {
    int64_t now = std::chrono::steady_clock::now().time_since_epoch().count();
#ifdef _WIN32
    srand(now);
#else
    mRandState[0] = (now >> 0) & 0xFFFF;
    mRandState[1] = (now >> 16) & 0xFFFF;
    mRandState[2] = (now >> 32) & 0xFFFF;
#endif
    ALOGV("initializing random seed using %lld", (unsigned long long)now);
}

void BlobCache::set(const void* key, size_t keySize, const void* value,
        size_t valueSize) {
    if (mMaxKeySize < keySize) {
        ALOGV("set: not caching because the key is too large: %zu (limit: %zu)",
                keySize, mMaxKeySize);
        return;
    }
    if (mMaxValueSize < valueSize) {
        ALOGV("set: not caching because the value is too large: %zu (limit: %zu)",
                valueSize, mMaxValueSize);
        return;
    }
    if (mMaxTotalSize < keySize + valueSize) {
        ALOGV("set: not caching because the combined key/value size is too "
                "large: %zu (limit: %zu)", keySize + valueSize, mMaxTotalSize);
        return;
    }
    if (keySize == 0) {
        ALOGW("set: not caching because keySize is 0");
        return;
    }
    if (valueSize <= 0) {
        ALOGW("set: not caching because valueSize is 0");
        return;
    }

    std::shared_ptr<Blob> dummyKey(new Blob(key, keySize, false));
    CacheEntry dummyEntry(dummyKey, NULL);

    while (true) {
        auto index = std::lower_bound(mCacheEntries.begin(), mCacheEntries.end(), dummyEntry);
        if (index == mCacheEntries.end() || dummyEntry < *index) {
            // Create a new cache entry.
            std::shared_ptr<Blob> keyBlob(new Blob(key, keySize, true));
            std::shared_ptr<Blob> valueBlob(new Blob(value, valueSize, true));
            size_t newTotalSize = mTotalSize + keySize + valueSize;
            if (mMaxTotalSize < newTotalSize) {
                if (isCleanable()) {
                    // Clean the cache and try again.
                    clean();
                    continue;
                } else {
                    ALOGV("set: not caching new key/value pair because the "
                            "total cache size limit would be exceeded: %zu "
                            "(limit: %zu)",
                            keySize + valueSize, mMaxTotalSize);
                    break;
                }
            }
            mCacheEntries.insert(index, CacheEntry(keyBlob, valueBlob));
            mTotalSize = newTotalSize;
            ALOGV("set: created new cache entry with %zu byte key and %zu byte value",
                    keySize, valueSize);
        } else {
            // Update the existing cache entry.
            std::shared_ptr<Blob> valueBlob(new Blob(value, valueSize, true));
            std::shared_ptr<Blob> oldValueBlob(index->getValue());
            size_t newTotalSize = mTotalSize + valueSize - oldValueBlob->getSize();
            if (mMaxTotalSize < newTotalSize) {
                if (isCleanable()) {
                    // Clean the cache and try again.
                    clean();
                    continue;
                } else {
                    ALOGV("set: not caching new value because the total cache "
                            "size limit would be exceeded: %zu (limit: %zu)",
                            keySize + valueSize, mMaxTotalSize);
                    break;
                }
            }
            index->setValue(valueBlob);
            mTotalSize = newTotalSize;
            ALOGV("set: updated existing cache entry with %zu byte key and %zu byte "
                    "value", keySize, valueSize);
        }
        break;
    }
}

size_t BlobCache::get(const void* key, size_t keySize, void* value,
        size_t valueSize) {
    if (mMaxKeySize < keySize) {
        ALOGV("get: not searching because the key is too large: %zu (limit %zu)",
                keySize, mMaxKeySize);
        return 0;
    }
    std::shared_ptr<Blob> dummyKey(new Blob(key, keySize, false));
    CacheEntry dummyEntry(dummyKey, NULL);
    auto index = std::lower_bound(mCacheEntries.begin(), mCacheEntries.end(), dummyEntry);
    if (index == mCacheEntries.end() || dummyEntry < *index) {
        ALOGV("get: no cache entry found for key of size %zu", keySize);
        return 0;
    }

    // The key was found. Return the value if the caller's buffer is large
    // enough.
    std::shared_ptr<Blob> valueBlob(index->getValue());
    size_t valueBlobSize = valueBlob->getSize();
    if (valueBlobSize <= valueSize) {
        ALOGV("get: copying %zu bytes to caller's buffer", valueBlobSize);
        memcpy(value, valueBlob->getData(), valueBlobSize);
    } else {
        ALOGV("get: caller's buffer is too small for value: %zu (needs %zu)",
                valueSize, valueBlobSize);
    }
    return valueBlobSize;
}

static inline size_t align4(size_t size) {
    return (size + 3) & ~3;
}

size_t BlobCache::getFlattenedSize() const {
    size_t size = align4(sizeof(Header) + PROPERTY_VALUE_MAX);
    for (const CacheEntry& e :  mCacheEntries) {
        std::shared_ptr<Blob> const& keyBlob = e.getKey();
        std::shared_ptr<Blob> const& valueBlob = e.getValue();
        size += align4(sizeof(EntryHeader) + keyBlob->getSize() + valueBlob->getSize());
    }
    return size;
}

int BlobCache::flatten(void* buffer, size_t size) const {
    // Write the cache header
    if (size < sizeof(Header)) {
        ALOGE("flatten: not enough room for cache header");
        return 0;
    }
    Header* header = reinterpret_cast<Header*>(buffer);
    header->mMagicNumber = blobCacheMagic;
    header->mBlobCacheVersion = blobCacheVersion;
    header->mDeviceVersion = blobCacheDeviceVersion;
    header->mNumEntries = mCacheEntries.size();
    char buildId[PROPERTY_VALUE_MAX];
    header->mBuildIdLength = property_get("ro.build.id", buildId, "");
    memcpy(header->mBuildId, buildId, header->mBuildIdLength);

    // Write cache entries
    uint8_t* byteBuffer = reinterpret_cast<uint8_t*>(buffer);
    off_t byteOffset = align4(sizeof(Header) + header->mBuildIdLength);
    for (const CacheEntry& e :  mCacheEntries) {
        std::shared_ptr<Blob> const& keyBlob = e.getKey();
        std::shared_ptr<Blob> const& valueBlob = e.getValue();
        size_t keySize = keyBlob->getSize();
        size_t valueSize = valueBlob->getSize();

        size_t entrySize = sizeof(EntryHeader) + keySize + valueSize;
        size_t totalSize = align4(entrySize);
        if (byteOffset + totalSize > size) {
            ALOGE("flatten: not enough room for cache entries");
            return -EINVAL;
        }

        EntryHeader* eheader = reinterpret_cast<EntryHeader*>(&byteBuffer[byteOffset]);
        eheader->mKeySize = keySize;
        eheader->mValueSize = valueSize;

        memcpy(eheader->mData, keyBlob->getData(), keySize);
        memcpy(eheader->mData + keySize, valueBlob->getData(), valueSize);

        if (totalSize > entrySize) {
            // We have padding bytes. Those will get written to storage, and contribute to the CRC,
            // so make sure we zero-them to have reproducible results.
            memset(eheader->mData + keySize + valueSize, 0, totalSize - entrySize);
        }

        byteOffset += totalSize;
    }

    return 0;
}

int BlobCache::unflatten(void const* buffer, size_t size) {
    // All errors should result in the BlobCache being in an empty state.
    mCacheEntries.clear();

    // Read the cache header
    if (size < sizeof(Header)) {
        ALOGE("unflatten: not enough room for cache header");
        return -EINVAL;
    }
    const Header* header = reinterpret_cast<const Header*>(buffer);
    if (header->mMagicNumber != blobCacheMagic) {
        ALOGE("unflatten: bad magic number: %" PRIu32, header->mMagicNumber);
        return -EINVAL;
    }
    char buildId[PROPERTY_VALUE_MAX];
    int len = property_get("ro.build.id", buildId, "");
    if (header->mBlobCacheVersion != blobCacheVersion ||
            header->mDeviceVersion != blobCacheDeviceVersion ||
            len != header->mBuildIdLength ||
            strncmp(buildId, header->mBuildId, len)) {
        // We treat version mismatches as an empty cache.
        return 0;
    }

    // Read cache entries
    const uint8_t* byteBuffer = reinterpret_cast<const uint8_t*>(buffer);
    off_t byteOffset = align4(sizeof(Header) + header->mBuildIdLength);
    size_t numEntries = header->mNumEntries;
    for (size_t i = 0; i < numEntries; i++) {
        if (byteOffset + sizeof(EntryHeader) > size) {
            mCacheEntries.clear();
            ALOGE("unflatten: not enough room for cache entry headers");
            return -EINVAL;
        }

        const EntryHeader* eheader = reinterpret_cast<const EntryHeader*>(
                &byteBuffer[byteOffset]);
        size_t keySize = eheader->mKeySize;
        size_t valueSize = eheader->mValueSize;
        size_t entrySize = sizeof(EntryHeader) + keySize + valueSize;

        size_t totalSize = align4(entrySize);
        if (byteOffset + totalSize > size) {
            mCacheEntries.clear();
            ALOGE("unflatten: not enough room for cache entry headers");
            return -EINVAL;
        }

        const uint8_t* data = eheader->mData;
        set(data, keySize, data + keySize, valueSize);

        byteOffset += totalSize;
    }

    return 0;
}

long int BlobCache::blob_random() {
#ifdef _WIN32
    return rand();
#else
    return nrand48(mRandState);
#endif
}

void BlobCache::clean() {
    // Remove a random cache entry until the total cache size gets below half
    // the maximum total cache size.
    while (mTotalSize > mMaxTotalSize / 2) {
        size_t i = size_t(blob_random() % (mCacheEntries.size()));
        const CacheEntry& entry(mCacheEntries[i]);
        mTotalSize -= entry.getKey()->getSize() + entry.getValue()->getSize();
        mCacheEntries.erase(mCacheEntries.begin() + i);
    }
}

bool BlobCache::isCleanable() const {
    return mTotalSize > mMaxTotalSize / 2;
}

BlobCache::Blob::Blob(const void* data, size_t size, bool copyData) :
        mData(copyData ? malloc(size) : data),
        mSize(size),
        mOwnsData(copyData) {
    if (data != NULL && copyData) {
        memcpy(const_cast<void*>(mData), data, size);
    }
}

BlobCache::Blob::~Blob() {
    if (mOwnsData) {
        free(const_cast<void*>(mData));
    }
}

bool BlobCache::Blob::operator<(const Blob& rhs) const {
    if (mSize == rhs.mSize) {
        return memcmp(mData, rhs.mData, mSize) < 0;
    } else {
        return mSize < rhs.mSize;
    }
}

const void* BlobCache::Blob::getData() const {
    return mData;
}

size_t BlobCache::Blob::getSize() const {
    return mSize;
}

BlobCache::CacheEntry::CacheEntry() {
}

BlobCache::CacheEntry::CacheEntry(
        const std::shared_ptr<Blob>& key, const std::shared_ptr<Blob>& value):
        mKey(key),
        mValue(value) {
}

BlobCache::CacheEntry::CacheEntry(const CacheEntry& ce):
        mKey(ce.mKey),
        mValue(ce.mValue) {
}

bool BlobCache::CacheEntry::operator<(const CacheEntry& rhs) const {
    return *mKey < *rhs.mKey;
}

const BlobCache::CacheEntry& BlobCache::CacheEntry::operator=(const CacheEntry& rhs) {
    mKey = rhs.mKey;
    mValue = rhs.mValue;
    return *this;
}

std::shared_ptr<BlobCache::Blob> BlobCache::CacheEntry::getKey() const {
    return mKey;
}

std::shared_ptr<BlobCache::Blob> BlobCache::CacheEntry::getValue() const {
    return mValue;
}

void BlobCache::CacheEntry::setValue(const std::shared_ptr<Blob>& value) {
    mValue = value;
}

} // namespace android
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/*
 ** Copyright 2011, The Android Open Source Project
 **
 ** Licensed under the Apache License, Version 2.0 (the "License");
 ** you may not use this file except in compliance with the License.
 ** You may obtain a copy of the License at
 **
 **     http://www.apache.org/licenses/LICENSE-2.0
 **
 ** Unless required by applicable law or agreed to in writing, software
 ** distributed under the License is distributed on an "AS IS" BASIS,
 ** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 ** See the License for the specific language governing permissions and
 ** limitations under the License.
 */

#ifndef ANDROID_BLOB_CACHE_H
#define ANDROID_BLOB_CACHE_H

#include <stddef.h>

#include <memory>
#include <vector>

namespace android {

// A BlobCache is an in-memory cache for binary key/value pairs.  A BlobCache
// does NOT provide any thread-safety guarantees.
//
// The cache contents can be serialized to an in-memory buffer or mmap'd file
// and then reloaded in a subsequent execution of the program.  This
// serialization is non-portable and the data should only be used by the device
// that generated it.
class BlobCache {
public:
    // Create an empty blob cache. The blob cache will cache key/value pairs
    // with key and value sizes less than or equal to maxKeySize and
    // maxValueSize, respectively. The total combined size of ALL cache entries
    // (key sizes plus value sizes) will not exceed maxTotalSize.
    BlobCache(size_t maxKeySize, size_t maxValueSize, size_t maxTotalSize);

    // set inserts a new binary value into the cache and associates it with the
    // given binary key.  If the key or value are too large for the cache then
    // the cache remains unchanged.  This includes the case where a different
    // value was previously associated with the given key - the old value will
    // remain in the cache.  If the given key and value are small enough to be
    // put in the cache (based on the maxKeySize, maxValueSize, and maxTotalSize
    // values specified to the BlobCache constructor), then the key/value pair
    // will be in the cache after set returns.  Note, however, that a subsequent
    // call to set may evict old key/value pairs from the cache.
    //
    // Preconditions:
    //   key != NULL
    //   0 < keySize
    //   value != NULL
    //   0 < valueSize
    void set(const void* key, size_t keySize, const void* value,
            size_t valueSize);

    // get retrieves from the cache the binary value associated with a given
    // binary key.  If the key is present in the cache then the length of the
    // binary value associated with that key is returned.  If the value argument
    // is non-NULL and the size of the cached value is less than valueSize bytes
    // then the cached value is copied into the buffer pointed to by the value
    // argument.  If the key is not present in the cache then 0 is returned and
    // the buffer pointed to by the value argument is not modified.
    //
    // Note that when calling get multiple times with the same key, the later
    // calls may fail, returning 0, even if earlier calls succeeded.  The return
    // value must be checked for each call.
    //
    // Preconditions:
    //   key != NULL
    //   0 < keySize
    //   0 <= valueSize
    size_t get(const void* key, size_t keySize, void* value, size_t valueSize);


    // getFlattenedSize returns the number of bytes needed to store the entire
    // serialized cache.
    size_t getFlattenedSize() const;

    // flatten serializes the current contents of the cache into the memory
    // pointed to by 'buffer'.  The serialized cache contents can later be
    // loaded into a BlobCache object using the unflatten method.  The contents
    // of the BlobCache object will not be modified.
    //
    // Preconditions:
    //   size >= this.getFlattenedSize()
    int flatten(void* buffer, size_t size) const;

    // unflatten replaces the contents of the cache with the serialized cache
    // contents in the memory pointed to by 'buffer'.  The previous contents of
    // the BlobCache will be evicted from the cache.  If an error occurs while
    // unflattening the serialized cache contents then the BlobCache will be
    // left in an empty state.
    //
    int unflatten(void const* buffer, size_t size);

private:
    // Copying is disallowed.
    BlobCache(const BlobCache&);
    void operator=(const BlobCache&);

    // A random function helper to get around MinGW not having nrand48()
    long int blob_random();

    // clean evicts a randomly chosen set of entries from the cache such that
    // the total size of all remaining entries is less than mMaxTotalSize/2.
    void clean();

    // isCleanable returns true if the cache is full enough for the clean method
    // to have some effect, and false otherwise.
    bool isCleanable() const;

    // A Blob is an immutable sized unstructured data blob.
    class Blob {
    public:
        Blob(const void* data, size_t size, bool copyData);
        ~Blob();

        bool operator<(const Blob& rhs) const;

        const void* getData() const;
        size_t getSize() const;

    private:
        // Copying is not allowed.
        Blob(const Blob&);
        void operator=(const Blob&);

        // mData points to the buffer containing the blob data.
        const void* mData;

        // mSize is the size of the blob data in bytes.
        size_t mSize;

        // mOwnsData indicates whether or not this Blob object should free the
        // memory pointed to by mData when the Blob gets destructed.
        bool mOwnsData;
    };

    // A CacheEntry is a single key/value pair in the cache.
    class CacheEntry {
    public:
        CacheEntry();
        CacheEntry(const std::shared_ptr<Blob>& key, const std::shared_ptr<Blob>& value);
        CacheEntry(const CacheEntry& ce);

        bool operator<(const CacheEntry& rhs) const;
        const CacheEntry& operator=(const CacheEntry&);

        std::shared_ptr<Blob> getKey() const;
        std::shared_ptr<Blob> getValue() const;

        void setValue(const std::shared_ptr<Blob>& value);

    private:

        // mKey is the key that identifies the cache entry.
        std::shared_ptr<Blob> mKey;

        // mValue is the cached data associated with the key.
        std::shared_ptr<Blob> mValue;
    };

    // A Header is the header for the entire BlobCache serialization format. No
    // need to make this portable, so we simply write the struct out.
    struct Header {
        // mMagicNumber is the magic number that identifies the data as
        // serialized BlobCache contents.  It must always contain 'Blb$'.
        uint32_t mMagicNumber;

        // mBlobCacheVersion is the serialization format version.
        uint32_t mBlobCacheVersion;

        // mDeviceVersion is the device-specific version of the cache.  This can
        // be used to invalidate the cache.
        uint32_t mDeviceVersion;

        // mNumEntries is number of cache entries following the header in the
        // data.
        size_t mNumEntries;

        // mBuildId is the build id of the device when the cache was created.
        // When an update to the build happens (via an OTA or other update) this
        // is used to invalidate the cache.
        int mBuildIdLength;
        char mBuildId[];
    };

    // An EntryHeader is the header for a serialized cache entry.  No need to
    // make this portable, so we simply write the struct out.  Each EntryHeader
    // is followed imediately by the key data and then the value data.
    //
    // The beginning of each serialized EntryHeader is 4-byte aligned, so the
    // number of bytes that a serialized cache entry will occupy is:
    //
    //   ((sizeof(EntryHeader) + keySize + valueSize) + 3) & ~3
    //
    struct EntryHeader {
        // mKeySize is the size of the entry key in bytes.
        size_t mKeySize;

        // mValueSize is the size of the entry value in bytes.
        size_t mValueSize;

        // mData contains both the key and value data for the cache entry.  The
        // key comes first followed immediately by the value.
        uint8_t mData[];
    };

    // mMaxKeySize is the maximum key size that will be cached. Calls to
    // BlobCache::set with a keySize parameter larger than mMaxKeySize will
    // simply not add the key/value pair to the cache.
    const size_t mMaxKeySize;

    // mMaxValueSize is the maximum value size that will be cached. Calls to
    // BlobCache::set with a valueSize parameter larger than mMaxValueSize will
    // simply not add the key/value pair to the cache.
    const size_t mMaxValueSize;

    // mMaxTotalSize is the maximum size that all cache entries can occupy. This
    // includes space for both keys and values. When a call to BlobCache::set
    // would otherwise cause this limit to be exceeded, either the key/value
    // pair passed to BlobCache::set will not be cached or other cache entries
    // will be evicted from the cache to make room for the new entry.
    const size_t mMaxTotalSize;

    // mTotalSize is the total combined size of all keys and values currently in
    // the cache.
    size_t mTotalSize;

    // mRandState is the pseudo-random number generator state. It is passed to
    // nrand48 to generate random numbers when needed.
    unsigned short mRandState[3];

    // mCacheEntries stores all the cache entries that are resident in memory.
    // Cache entries are added to it by the 'set' method.
    std::vector<CacheEntry> mCacheEntries;
};

}

#endif // ANDROID_BLOB_CACHE_H
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